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Dishwasher Not Draining: Causes and How to Fix

dishwasher not draining
Jan 2021

The dishwasher, one of your most essential kitchen appliances, is usually an afterthought. After months (or perhaps years) in service, it is just there – always ready to do all the cleaning at your whim. One day, you open the door to see sudsy water at the bottom. “Cringe” is only one of the many words to describe your feeling as you start the wash cycle again. The confirmation comes later that your dishwasher not draining is a nightmare you have to face. Before calling a plumber or technician, try to determine the cause as some of them are easy to fix.

Most Common Causes and How to Fix Dishwasher Not Draining

Running the dishwasher for a second time is a smart thing to do if the dishwasher stops draining. Quite possibly, it might have been interrupted during the mid-cycle.
The first step towards finding a solution is to identify the problem. Once you are sure that your dishwater won’t drain, it is now possible to focus on the cause. Only then can appropriate steps be taken to repair – and some of these you can perform yourself.
Before you check the dishwasher, remember to do these safety precautions:

  1. Electric shock can cause a severe injury. For this reason, you should unplug the dishwasher from the power source.
  2. Turn off the water supply, especially when you have to work with some hoses.
  3. Get the owner’s manual. You may need it to locate dishwater components or references to replacement parts.

I. Dishwasher Detergent

dishwasher detergent

Did you happen to run out of dishwasher detergents and decided to use regular dishwashing liquid? Hopefully, you did not use laundry detergent as a substitute. Believe it or not, some people did.
Using the wrong detergent – especially those that produce suds – can cause the dishwasher not to drain. If this is the case, then run another cycle – this time, using the correct product.

II. Garbage Disposal

The dishwasher empties water through a drain hose attached to the garbage disposal drain. Clogging could occur if the garbage disposer accumulates bits and pieces of food or if food sludge settles in the drain pipe. It can happen if you do not leave the water running for 10 seconds or more after the food is gone – a practice that helps flush food materials in the P-trap drain. Consequently, it causes the dishwasher not to drain.
Try running the garbage disposal and see if it works.

III. Air Gap

If you do not have a garbage disposer, then there must be an air gap installed on the sink beside the faucet. It is a small cylinder most likely made of stainless steel acting as a vent to prevent an airlock in the dishwasher drain hose.
Should the dishwasher air gap get clogged, it might be the reason why your appliance stopped draining. You can find out for sure by twisting it counterclockwise to remove and visually inspect for an accumulation of gunk.
If you find food debris inside the air gap, use a stiff brush and water to clean. After replacing, run the dishwasher and see if it solves the problem.

Related article: Dishwasher Leaking: Top 7 Causes and How to Fix

Other Causes of Dishwasher Not Draining

If the simple fix mentioned above did not work, then the cause of your dishwasher draining is a little bit more complicated. Hopefully, the following steps resolve the issue.

I. Remove Standing Water

If the above measures do not work, then the cause of your dishwasher not draining is a little more complicated. You would need to remove the accumulated water (no matter how dingy it seems).
First, you should put towels (absorbent ones work best) around the dishwasher to absorb spills, then remove the bottom dish tray. Next, scoop the sudsy water using a plastic cup. When the standing water level is too low, sop the remaining water using towels.

II. Drain Basket

drain basket

At the bottom, inside the dishwasher, there is a drain basket that looks like an upside-down basket. A buildup of food particles can cause clogging. You can snap off or unscrew to remove the drain basket and then remove the debris.
Debris in the drain basket means that you load dirty dishes. Preventing a similar occurrence in the future is simple. Pre-rinse before loading them into the dishwasher.
Some brands make newer dishwasher models that have built-in macerators to grind bits of food particles. They market it as machines that do not entail pre-rinsing dishes. However, it does not work well for larger pieces, which is why you should still rinse the dishes first before loading.

III. Drain Hose

The dishwasher drain hose connects to the garbage disposal or the air gap. If it somehow gets kinked, that could hamper the draining process.
Check the drain hose to see if you can straighten and fix the problem. Once kinked, though, it becomes prone to kinking in the future on the same spot.
On the other hand, if the hose does not appear to be kinked, another possible issue is clogging. The only way to check is to detach it from the drain pump.
To do that, make sure to unplug the dishwasher from the power source. For good measure, put towels on the floor around the appliance because some water will spill.
Remove the lower front panel to access the drain pump, then detach the hose. At the opposite end, disconnect it from the air gap or garbage disposal. Look through the interior to see if there is a foreign object causing a blockage. If there is, you can remove using a screwdriver or straightened wire hanger.
At any rate, you also have the option of replacing the old hose with a new one if there are already signs of wear and tear.

drain hose

IV. Check Valve

Some models of dishwashers have a check valve attached to the drain outlet before the drain hose. Its purpose is to prevent dirty water from re-entering by ensuring that water flows out in one direction. During the wash or circulation cycle, the check valve, in the form of a rubber flapper, should be closed. It only opens during the drain cycle.
If wastewater is returning to the tub, then there might be a foreign object lodged into the check valve, which you can clear. Otherwise, it is likely defective and needs to be replaced. You can do it yourself, or seek professional help.

Mechanical Problems Causing the Dishwasher Not to Drain

If your dishwasher remains stubborn, refusing to drain water, the problem is far worse. Most likely, you need the services of an appliance repair professional. Some of these items are repairable, while others need outright replacement.
Timer. Some dishwasher models use a timer to operate the washing cycles. Besides controlling the pump motor, it also manages the drain solenoid or a drain pump motor.
Belt. Old models of dishwashers could be using a belt-driven pump. If it comes off or is slipping, the pump cannot operate properly.
Drain Pump and Motor. Drainage problems can be due to a faulty pump or motor. Yours may have a single motor pump or comes with a separate drain pump. Either way, this is a job that is best handled by trained technicians. Call Prime Appliance Repairs today!

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